Method of bleaching and/or dyeing foliage



Patented June 8, 1937 UNITED STATES PATENT OFFICE Henry Dux, Jacksonville, Fla.

N Drawing. Application April 1, 1936, Serial 6 Claims.

My inventionrelates to the art of bleaching foliage, particularly fresh foliage, and preferably combines this step with a simultaneously-conducted dyeing operation.

My present application constitutes a continuation-in-part of my copending application, Serial .No. 744,263, filed September 15th, 1934, and entitled Method of bleaching foliage.

In essence, my invention comprises a method, 10 characterized by its extreme simplicity, of rapidly and uniformly bleaching foliage, particularly fresh foliage, by the action of certain alcohols under the combined influence of elevated heat and superatmospheric pressure. Under certain conditions, it has been found that even the most bleaching-resistant foliage can be bleached completely and uniformly in half an hour, or even less; as compared with typical prior art processes not using a combination of elevated temperatures and pressures, and requiring upwards of four days or 98 hours, and this with less favorable end results.

Preferably, the bleaching step according to my process may be combined with simultaneous dyeing in the same operation, and for this purpose I prefer to use an aniline dye, which I have found will impart a fast, sharp, and permanent color to the foliage.

Among the fresh foliage, my process of bleaching is particularly efficacious in the bleaching of Asparagus plumosus (Florida grown asparagus ferns), mediolla, adiantum, and other species of fern and the like. The invention, however, is also applicable to dried foliage, although higher temperatures and pressures are required in this case.

My new process of bleaching is applicable alike to field-grown and greenhouse or hot house foliage, and bleaches completely and uniformly, regardless of the chemical contents of the foliage resulting from prior fertilization or spraying treatment, and regardless of the thickness of the stem, or differences betweenthe thickness of the stem and thickness of the leaves. In all cases a firm foliage is produced, extremely flexible and resistant to shattering.

The fact that preliminary spraying treatments have no inhibiting action on the efficacy of my process is of especial importance when it is considered that spraying materials in common use, such for example as calcium arsenate, together with chemical fertilizers, sand and hot sun, apparently form a hard coating of waxes, fats and gums on the stem of. some plants; such as .as-

paragus fern; which coating, until the introduction of my process, has rendered it impossible for the bleaching agent to penetrate and to bleach uniformly the plants, which if desired may be in preparation for after-treatments such as a separate dyeing step. I'have found that the alcohol, when under pressure, readily removes these coatings.

Briefly, my process comprises bleaching the fresh foliage in a primary aliphatic alcohol having less than three carbon atoms (either ethyl (CzHsOH) or methyl (CH3OH) alcohol) under pressure. The amount of pressure and the duration of the process are factors depending, within certain limits, upon the physical strength and resistance to bleaching of the particular foliage to treatments. Ifdesired, dyeing ingredients be incorporated directly into the bleaching bath, and to this end I preferably incorporate an aniline dye.

Using alcohol of the type mentioned in the foregoing, I have found that a pressure ranging between 3 to '7 pounds per square inch above Iatmospheric gives by far the best results, this pressure range corresponding to a temperature range of to F., when for example the pressure is built up from atmospheric pressure in a confined vessel by the application of heat.

Very occasionally I have employed with success pressures upwards of 25 pounds per square inch above atmospheric, (which is substantially the pressure at which I vfind that the plant life begins to disintegrate), for example in those cases where the stems of the material undergoing treatment are unusually thick or resistant. Usually, however, just as stated previously, I find that a pressure of from three to seven pounds above atmospheric gives far the best results, to such an extent that this range may be stated to be critical. are used, resulting in pressures lower than 3 to '7 pounds per square inch above atmospheric, spotty and unsatisfactory bleaching and dyeing results,

. while with higher temperatures (and thus with higher pressures) destruction of the foliage undergoing treatment may quite possibly occur.

Thus, in a broadly typical example, the plants to be treated are placed in pressure tanks with sufficient alcohol, either methyl or ethyl, to cover the foliage completely. The tanks are then closed and heated gradually until the internal pressure is at the desired value of say 3 to '7 pounds above atmospheric pressure.

The duration of this pressure treatment, is,

If temperatures lower than 115 to 145 F., u

as suggested above, in the neighborhood of onehalf to one hour, depending on the particular pressure used, and the quality of foliage being treated. For example, with a particular type of foliage, if a lower pressure is employed, the time of the process must be lengthened, and vice versa.

Because of such treatment, the alcohol under pressure has been found to penetrate the fibres of the foliage thoroughly, even including the stems, and in a comparatively short time. The process is found to remove all traces of chlorophyl (green coloring matter) from the foliage.

The penetration of the alcohol includes the stems as well as the lighter branches, and the resultant bleached product is perfectly uniform and ready for conventional dyeing or other subsequent treatment. This subsequent dyeing, if conducted separately, may be carried out by any usual process; and if it is desired to preserve the bleached foliage, any usual preserving process can be employed. I might add at this point that the use of pressure marks a difference between a process which can be duplicated successfully at any desired time, and which produces a completely and uniformly bleached foliage which is otherwise substantially unchanged, on the one hand; and the prior art processes which do not necessarily produce uniform bleaching, so that the product very frequently will have a somewhat mottled appearance, are not uniformly reproducible at will.

In a particular case, given solely by way of example, and not as imparting any limitation, and in which I desire to produce dyeing as well as bleaching, I mix a bath in the proportions of /g gram of green aniline dye to one gallon of alcohol, together with one ounce by weight of yellow aniline dye, the dye thus being seen to be in solution from the beginning of the process. My experiments show that on an average, about four ounces by volume of this solution are required for each pound of asparagus fern, though I prefer to use a considerable excess of the solution. The exact theoretical quantity of solution per pound of any particular material can be found only by experiment, the proportions used in the preliminary run of course being dictated by the experience of the operator. Certain asparagus ferns for example have been found to require one hour for bleaching and dyeing at the temperature and pressures indicated. The time of the run may be lengthened or shortened, as thecase may be, by decreasing or increasing the temperature and pressure, but the risk is encountered of mottled bleaching and dyeing, or disintegration of the foliage, respectively.

The approximately proper amount of solution and the .foliage to be treated are placed in a pressure tank, initially at room temperature, and

after this charge is sealed therein, the temperature is raised to from -145 F. (depending on the resistance of the material being treated), thus giving rise to the desired pressure of from 3 to 7 pounds per square inch above atmospheric, at which temperature and pressure ranges the alcohol will dissolve the natural coloring matter of the foliage and thus will produce the desired bleaching action. This temperature I have found to be suflicient to produce satisfactory and permanent dyeing, with vivid green coloring, of the foliage. Of course, any surplus dye on the exterior of the foliage naturally will wash off, without however, disturbing the color to which the material undergoing treatment has been dyed.

I find that grain, or ethyl alcohol is slightly superior for my purposes, but since the price is prohibitive, I prefer to use either synthetic or wood alcohol, which have more lasting stamina in bleaching.

My research has also indicated that it is far preferableto use an alcohol which initially is as free as possible from water. If the alcohol contains more than a certain quantity of water it will not bleach properly. For example, if the alcohol falls below 172 proof, it can-no longer be used for bleaching, since as little as 12% of water will cook the foliage at the temperature and pressure employed, and the leaves will fall off. The desirability of using alcohol initially as free from water as possible is emphasized when it is considered that even when starting with alcohol at nearly 200 proof, the water which is in the fresh foliage being treated weakens the alcohol, so that the solution can be used, at the most, only for fromfour to six bleachings, at which time it must be redistilled.

That portion of the alcohol which is employed to dissolve the coatings on the ferns, etc. is not available for dissolving the coloring matter in plant life; and suflicient alcohol must be provided for in the four ounce per pound of asparagus fern figure previously stated, to accomplish both of the said dissolving operations.

The quantity of solution used up in any given bath is determined by checking the quantity present before and after the bath; and the quantity lost or used up is replaced after each operation, up through four to six operations employing the main bath, at which time the entire batch remaining is replaced. None of the solution is lost by evaporation.

While Asparagus plumosus is substantially the same as Florida grown asparagus ferns, the latter grow in the open, rather than in the greenhouse, and hence are much hardier, and therefore are much harder to bleach.

In addition to the enormous saving in time accomplished by my process, as pointed out hereinbefore, my process is characterized by. the much larger batches which I can treat. For example, a uniform product is obtained, even if the bundles of material are laid one on top of each other Y to a depth of twelve inches, or even more.

Once the broad aspects of my invention are adaptations will readily occur to those skilled in the art. Accordingly, I intend to be limited only by the scope of the appended claims.

I claim:

1. The process of bleaching fresh foliage comprising subjecting the same to the action of primary aliphatic alcohol having less than three carbon atoms under pressure ranging from 3 to as high as 7 pounds per square inch above atmospheric, depending upon the age and nature of the foliage being bleached, at temperatures of from 115 to F., until the bleaching is complete.

2. The process of bleaching fresh foliage, comprising placing the foliage in a pressure tank, adding primary aliphatic alcohol having less than three carbon atoms until the foliage is completely covered, closing the tank, applying heat of from 115 to 145 F. until the pressure is brought to a desired value ranging from approximately 3 to 7 pounds above atmospheric pressure, depending upon the age and nature of the foliage being bleached, andmaintaining the pressure at the a desired value until the bleaching is complete.

3. The process of bleaching fresh foliage, comprising subjecting-the same to the action of substantially water-free primary aliphatic alcohol having less than three carbon atoms, at temperatures of from 115 to 145 F. and under pressure ranging from 3 to 7 pounds per square inch above atmospheric until the bleaching is complete.

4. The process of bleaching and dyeing foliage, comprising subjecting the foliage to the action of a solution consisting of a dyestufi and a primary aliphatic alcohol having less than three carbon atoms, under pressure ranging from 3 to as high as 7 pounds per square inch above, atmospheric, depending on the age and nature of the foliage undergoing treatment, at temperatures of from 115 to 145 F., until the bleaching and dyeing are complete.

5. The process of bleaching Florida grown asparagus fern, comprising subjecting the Florida grown asparagus fem to the action of primary aliphatic alcohol having less than three carbon atoms, under pressure ranging from 3 to 7 pounds per square inch above atmospheric, at temperatures ranging from 115 to 145 F., until the bleaching is complete.

6. The process of bleaching and dyeing foliage in a single bath, comprising placing the foliage in a bath consisting of gram of green aniline dye to 1 gallon of primary aliphatic alcohol containing less than three carbon atoms, of 172 proof or better, and 1 ounce by weight of yellow aniline dye, all in solution, and maintaining the bath at a temperature of from 115 to 145 F. and a pressure of from 3 to '7 pounds per square inch atmospheric, until the bleaching and dyeing are complete.

HENRY DUX. 

